Various vehicles, such as spacecraft and aircraft carry a substantial quantity of electronic gear necessary to assure proper operation of the craft. During operation of the electronic gear, substantial quantities of heat are generated and to protect the equipment, it is necessary that some means be provided for cooling the equipment.
Cooling can be obtained by flowing a coolant in heat transfer relation to the heat load to be cooled with the heat load rejecting heat to the coolant which rises in temperature and elsewhere in the system has the acquired heat rejected. While such cooling can be effected without changing the phase of the coolant, as is well known, substantially greater quantities of heat can be exchanged for a given coolant flow where the coolant undergoes a phase change, normally from the liquid phase to the vapor phase since, in addition to whatever heat is taken up by a change in temperature of the coolant, the generally much greater heat of vaporization is also taken up from the heat load.
While many proposals have been made for cooling various heat loads such as electronic gear by evaporation, most are not susceptible to ready employment in unusual gravitational conditions as are encountered by spacecraft or high performance aircraft at various times in their operation.
In the case of zero gravity conditions, such as are encountered by spacecraft, the liquid phase of the coolant will literally float within its flow path within an evaporator without necessarily coming into good heat transfer relationship with an evaporator boundry or wall through which heat transfer must occur. Consequently, the rate of heat transfer to the liquid phase may be substantially impeded reducing the thermal efficiency of the evaporator.
In the case of high gravitational loading as is encountered in high performance aircraft, particularly when undergoing abrupt changes in attitudes or performing aerobatic maneuvers, the large forces involved will be applied to the liquid phase of the coolant and drive the same against some part of the heat transfer boundry of the evaporator leaving other parts of the boundry literally starved of the liquid phase of the coolant to be evaporated thereat. Again, heat transfer efficiency can be considerably lowered.
The present invention is directed to overcoming one or more of the above problems.